1. Field of the Invention
This invention relates to an impact printer using a print element and to the print element.
2. Description of the Prior Art
An impact printer, such as a typewriter or the like, now generally uses a print element 1 having a daisy wheel-like or a cup-like shape as shown in FIG. 1. The print element 1 in FIG. 1 comprises a disc-shaped base 2, a number of resilient rod-like spokes 3 extending upwardly from the disc and juxtaposed radially or in a cup-like manner, and type elements 4a and 4b provided in two rows at the upper end of each spoke 3, the base 2 having a center bore 7 into which a center shaft 6 having a mounting portion 5 is insertable so that the print element 1 is detachably mountable on the mounting portion 5 and a positioning bore 9 into which a positioning pin 8 is insertably fitted. The mounting portion 5 for the print element 1 is often connected directly to a motor shaft 10. But in some cases, it is provided on a rotary member which is connected to the motor shaft 10 by gears or the like to reduce the rotational speed in order to match the inertia of print element 1 with that of the rotor of the motor 11. In any case, the print element 1 and the rotary member having the mounting portion 5 should be aligned with each other with accuracy. Hence, it is troublesome and takes much time to exchange the print element 1 for the reason that the print element 1, when mounted, is limited as to its position and inevitably must be mounted or removed from above, and a printing hammer may escape from the position shown in the drawing during the exchanging of the print element 1.
Also, a shift mechanism 15, comprising a rotary solenoid 13 and a cam lever 14 or the like and used for vertically moving the print element 1, must be disposed outside the print element 1, so that it is difficult to make the printing small-sized.